The two major objectives of this proposal are to elucidate the structure of cell membranes and to study the mechanism of hormone action at the membrane level. It is proposed to examine the arrangement of the amino-phospholipids and proteins in various membranes by use of penetrating and non-penetrating chemical probes and cross-linking probes which react with amino groups. This study is aimed to determine how many of the amino-phospholipids are oriented on the inner and outer surface of the membrane, the neighbor frequency of these phospholipids, how many amino-phospholipids are closely associated with proteins and which specific proteins bind these polar lipids. Perturbation of the membrane by chemical and physical agents will be followed by use of these chemical probes. The mechanism of hormone action on cell membranes will be carried out by a study of hormone binding to isolated erythrocytes, rat heart ventricle membranes and isolated fat cells from rats and humans. The binding of catecholamines, alprenolol and propranolol will be correlated with adenylate cyclase activity, lipolysis, and calcium binding. Insulin, glucagon, alprenolol and catecholamine binding will be studied in fat cells from obese and diabetic humans and compared to normals to see if hormone binding is altered. The influence of thyroxine on glucagon, alprenolol and catecholamine binding and hormone response in isolated fat cells and cardiac muscle will be studied in order to elucidate the "permissive action" of thyroxine on the catecholamine response in adipose tissue and heart. Structure-function relationships with catecholamines and with beta-adrenergic antagonists will be studied by comparing the binding of various catecholamine analogs with their ability to alter the binding of the catecholamines and the beta-antagonists. Alpha and beta adrenergic blockers will be studied to see which ones influence catecholamine binding and which ones influence catecholamine beta-receptor protein from the erythrocyte membrane. BIBLIOGRAPHIC REFERENCES: S. E. Gordesky, G. V. Marinetti and R. Love "The Reaction of Chemical Probes with the Erythrocyte Membrane", J. Memb. Biol. 20, 111, (1975). L. Lesko and G. V. Marinetti "Hormone Action at the Membrane Level IV. Epinephrine Binding to Rat Liver Plasma Membranes and Rat Epididymal Fat Cells", BBA 382, 419 (1975).